1. Field of the Invention
The present invention is generally related to medical devices and methods. More particularly, the present invention relates to vascular introducer sheaths incorporating improved passive valves that can maintain hemostasis around medical instruments.
Vascular introducer sheaths are well known components of vascular access systems that are used in a wide variety of diagnostic and therapeutic vascular procedures. For example, introducer sheaths are used in a number of minimally invasive procedures such as endovascular procedures and laparoscopic surgery. Of specific interest relative to the present invention is the endovascular placement of grafts, stents, stent-grafts, and other endoluminal prostheses. Such procedures are often performed through vascular access systems that include an introducer sheath to provide access to a body lumen (e.g., blood vessels), cavity, or organ. A sealing valve typically is located at a proximal portion of the introducer sheath. When medical instruments or tools are inserted into or withdrawn from the sealing valve, the valve generally prevents fluid from inadvertently leaving (e.g., back bleeding) or entering the body lumen through the introducer sheath.
Current introducer sheath valves generally fall into two basic categories: passive and active. A passive valve generally relies on the deformation of a resilient sealing body by the medical instrument inserted through the valve to form the desired fluid tight seal. Active medical valves include a mechanism that moves a sealing body into contact with the traversing medical instrument.
A wide variety of passive and active sealing valve structures for use with introducer sheaths have been proposed. These structures provide different hemostatic valve designs that typically vary in terms of the valve shape, aperture or slit geometry, aperture or slit position, and other design aspects. While these structures have met with varying degrees of success and acceptance, they generally still suffer from disadvantages of leakage around the sealing valve.
For these and other reasons, it is desirable to provide improved introducer sheath hemostatic valves for use in endovascular, laparoscopic, and other medical procedures. It would be particularly desirable if these improved valves provide enhanced hemostasis sealing (i.e., preventing leakage of fluid from or into the introducer sheath), maximize safety, and do not require any actuation in the various modes of operation. It would be further desirable if these improved valve structures were better adapted for passing instruments both distally and proximally therethrough as well as for providing a fluid-tight seal across a wide range of medical instrument diameters.
2. Description of the Background Art
Valve sealing structures for sheaths, catheters, cannulas, trocar assemblies, sheaths, and other medical devices are described in U.S. Pat. Nos. 4,978,341; 5,350,364; 5,391,154; 5,456,284; 5,603,702; 5,722,958; 5,865,807; 5,916,198; 5,935,112; 5,989,233; 6,276,661 B1; and 6,520,939 B2, in U.S. Publication No. US 2003/0014015 A1, and in PCT Publication No. WO 03/008035 A1.
The full disclosures of each of the above references are incorporated herein by reference.